Self-aligning rotary electrical switch



Jan. 19, 1960 D. o. DULUDE 2,921,996

SELF-ALIGNING ROTARY ELECTRICAL SWITCH Filed Jan. 25, 1958 2Sheets-Sheet 1 INVENTOR. DONALD O. DULUDE ATTORNEYS Jan. 19, 1960 D. o.DULUDE SELF-ALIGNING ROTARY ELECTRICAL SWITCH 2 Sheets-Sheet 2 FiledJan. 25, 1958 INVENTOR. DONALD O. DULUDE 25m fi l. M WW FIG. 3

ATTORNEYS United States Patent 2,921,996 SELF-ALIGNING ROTARY ELECTRICALswrrcn Donald 0. Dulude, Rochester, Mich., assignor to Kuhlman ElectricCompany, Birmingham, Mich., a corporation of Michigan ApplicationJanuary 23, 1958, Serial No. 710,734 3 Claims. Cl. 200-11 This inventionrelates to. rotary electrical switches and more particularly to a rotaryswitch construction adapted for use in high potential circuits such asis required of transformer .tap changers, for example, and in which theelectrically conductive contact parts of the rotor are self-adjustableto assure uniform contact pressure in the event of misalignment of thecontact parts with which the rotor mounted contacts cooperate.

Switches of the general class to which the invention relates and in useheretofore customarily include a'plurality of stationary contactsconnected to selected current-carrying parts of electrical apparatussuch as a transformer, for example, and mounted on a supporting panel inarcuate or circular form. Such constructions also include a rotatablebridging device composed of one or more generally segment-shaped platesprovided with one or more contact parts, the arrangement being such thatthe contact part or parts on the bridging device are capable of spanningthe distance between and engaging any two adjacent stationarycontacts onthe panel. In some of the prior switch constructions, the contactscarried by the bridging device have been arranged to straddle a pair ofstationary contacts and lie in substantially parallel planes so as toenable magnetic force to add to the mechanical force with which thestationary contacts are gripped by the bridging contacts.

In the known constructions ditficulty has been experienced in obtaininguniform contact pressure between the bridging contacts and the twoadjacent contacts of the stationary contacts. One of the principalsources of difiiculty in this respect is due to misalignment of thestationary contacts, that is, one of the stationary contacts may not bein exactly the same plane as the other. When two such misalignedcontacts are bridged by the bridging contacts, considerably morepressure will be exerted on one stationary contact than on the other,with the result that excessive wear of the contacts occurs, or infirmengagement is obtained between the bridging contacts and one of thestationary contacts, or both.

An object of the invention is to provide a rotary switch constructionwhich overcomes the disadvantages previously referred to of switches inuse heretofore.

Another object of the invention is to provide a rotary switchconstruction in which the stationary and bridging contact elements areso constructed and arranged as to be capable of relative movement so asto compensate for misalignment of the stationary contacts.

A further object of the invention is to provide a selfaligning rotaryswitch construction in which the stationary and movable contact elementsare capable of substantially universal relative movement within limitsso as automatically to assure uniform contact pressure of the movableand stationary contact elements.

Still a further object of the invention is to provide a rotary switchconstruction of the kind referred to in which the movable bridgingcontacts are arranged to straddle the stationary contacts and areyieldably urged towards one another so as to grip the stationarycontacts therebetween.

Other objects and advantages of the invention will be pointed outspecifically or will become apparent from the following description whenit is considered in conjunction with the appended claims and theaccompanying drawings, in which:

Figure 1 is a view partly in plan and partly in section of the elementsof a rotary switch constructed and arranged in accordance with oneembodiment of the invention;

Figure 2 is a fragmentary, enlarged elevational view of the apparatusshown in Figure 1;

Figure 3 is an end elevation of one of the movable contact elementssupported on its rotor part in accordance with the invention;

Figure 4 is a view similar to Figure 1, but disclosing a modified formof the invention; and

Figure 5 is a fragmentary, enlarged view partly in elevation and partlyin section of the construction shown in Figure 4.

Apparatus constructed in accordance with the embodiment of the inventionshown in Figures 1 and 2 comprises a mounting panel 1 formed of anysuitable insulating material such as laminated nylon, phenolic materialsuch as Bakelite, or any other suitable substance, and on which ismounted a plurality of stationary contact elements 2 formed of suitableelectrically conductive material such as copper. As is best shown inFigure 1, the contact elements 2 are arranged in arcuate or circularform and each of the contact elements is mounted on the panel 1 by meansof a metallic, headed bolt 3 and an annulus or ring 4 formed of thesamematerial as the mounting panel 1. Each of the contact elements 2 andthe annulus 4 are provided with aligned openings to accommodate theshanks of the bolts 3, the headed ends of the bolts bearing against therespective contacts 2 and the other end of the bolts being threaded asat 5 for reception of retaining nuts 6. One end of a currentcarryingpart 7 leading from a transformer or the like (not shown) also may beconnected to each bolt 3 and removably anchored to the latter by ananchor nut 8, whereby the part 7 is electrically connected to theassociated contact element 2. Each of the contact elements 2 may have ablind opening 9 therein adapted to register with a similar opening 10formed in the annulus 4, the openings 9 and 10 normally receiving ananchor pin 11 which reacts between the contact element 2 and the annulus4 to prevent rotation of the contact element about the axis of the bolt3.

At the center of the are or circle defined by the several contactelements 2 the mounting panel 1 maybe provided with an opening 12 inwhich is rotatably mounted a driving shaft 13 which preferably is formedof insulating material similar to that previously referred to. Suitablemeans such as a crank or wheel (not shown) may be fixed at one end ofthe driving member 13 for rotating the latter when desired.

In the embodiment of the invention disclosed in Figures 1 andl, theswitch includes a bridging device 14 composed of a pair of supportingmembers or plates 15 formed of non-conductive material of the kindpreviously referred to and spaced apart from each other. Each of themounting plates 15 is cut away at one end as at 16 so as to form a pairof leg sections 17 adapted to straddle the driving shaft 13. The legsection 17 of each supporting plate is provided with aligned openings 18adapted for reception of either a metallic or non-metallic mounting pin19 which also passes through an opening in the driving shaft 13 so asrockably to connect each mounting plate 15 to the driving shaft formovement with the latter. The

-wall.of the opening .16 so as to enable each plate 15 to partakeof'limited rocking movement about the axis of its pin 19. 1f .desiredthe retention of the pin 19 may be assured by atapered orother suitablyconstructed locking plin,21 extending through openings in one leg 17 ofeach indilnting plate 15 and in the pin 19, the latter openingbeing'located at right angles to the opening18.

The supporting members 15 are so connected to the drive shaft 'lj3thatthey are superposed and extend radially from the drive shafttowards'tihe are or circle defined by the stationary contact elements 2.The radially outermost end of each of the mounting plates 15 is providedwith an extension or jledge '22which projects beyond the remainder ofthe plate 15 and the outer face of each plate 15 isibored astat 23 forreception of one end of a mounting post 24. Adapted to be mounted on theradially outer end of each mounting plate 15 is a bridging contactmember 25 formed of suitable electrically conductive material such ascopper and, each contact member 25 is provided with a substantiallycentrally located bore'26 of'such size as 'r'otatablyto receive theshank of the mounting post 24. The outer end of the post 24 is headed asat 27 so as to prevent inadvertent separation of the contact member 25and 'the associated mounting plate 15 and the mounting I post'24 isremovably retained in assembled relation with its associated mountingplate 15 by means of an anchor pin 28 which extendsthrough alignedopenings in the mounting plate and the mounting post 24. The size andarrangement of each of the contact members 25 are such that a'-"smallgap22a'exists between the member and its associated ledge 22 when the'partsare assembled. The gap 22a permits each contact 25 to be rocked aboutthe axis-of the post 24, for a purpose to be pointed out, and

the rockable mounting of the contacts 25 and the support- I ing' plates15 enables each contact to partake of substantially universal, butlimited movement.

. The spacing of the two mounting plates 15' during normal operatingconditions is such that the two adjacent contact elements 2 bridged bythe contact members 25 are sandwiched between the latter as is shown inFigure ,2 In the preferredconstruction each of the mountingplates 15 islockable about the axis of its associated mounting'pin' 19, as has beenpointed out, so in order toassure g'oodcontact between the stationarycontact ele ments and-both bridging contact members 25, yieldablemeansgener'ally indicated by the reference character 29 is incorporatedin the apparatus for yieldably biasing the mounting plates 15 and thecontact members 25 towards a one another. The biasing means disclosed inFigures 1 and2 may comprisea bolt 30 extending through aligned openings31 in the mounting plates 15 and having a head 32 atione end adapted tobear against one of the plates 15. The bolt 30 may receive a washer 33adjacent to its other endcarranged tovbear against the other mountingplate 15 and the boltalso'receives a spring 34 arranged to reactbetween-the washer 33 and a similar washer 33a which may besadjustedlongitudinally of the bolt by a threaded nut.35. Adjustment of the nut35 on the bolt 30 will vary 'theforce with which the mountingplates 15and their associated contacts 25 are urged towards one another.

In the operation of the embodiment disclosed in Figures '1, 2- and .3;the driving shaft 13 may be rotated so as to cause-the contacts 25 tobridge any two adjacent stationcontacts2 and engage the latter onopposed surfaces as is shown in Figure 2. In an ideal construction, theopposedsurfaces of the-stationary contacts 2 will be perfectly parallel.with each other and with, the surface 1a of the mounting panel 1'. Inactual practice, however, the opposed surfaces of the stationarycontacts 2'may'not be parallel witheaoh other or with the adjacentsurface of the mounting panel,.and the stationary contacts 2 of anygiven pair .ofacontacts may be somewhat misaligned so 4 V v 7 that theyare not located in the same place. In either event, firm contact betweenthe bridging contacts 25 and any two adjacent stationary contacts 2 isassured, due to the ability of each contact 25 to rock about the axis of'its mounting post 24 which, as is best'illustrated in Figure 7 2, liesin a plane substantially parallel to the plane of the surface In of thelongitudinal panel 1. Positive engagement between the bridging contactsand the stationary contacts further is assured bythe yieldable biasingmeans 29. As a result, good electrical connection between two adjacentstationary contacts 2 is provided.

Rotary switches of the kind to which the invention relates generally aremanufactured, carefully, so' the mis aligment of any two adjacentstationary contacts 2 usually will be of fairly small degree.Accordingly, the degree of rocking movement of the movable contacts 25,and the plates 15 need not be great. However, the sizes of the gaps 2iand 22a may be as' large as necessary to produce the desired results. iv t In order to assure smooth operation of the switch when the bridgingdevice is rotated, the ends of the contacts 25 are rounded as at 25a topermit them to ride smoothly over the fixed contacts 2 in eitherdirection of rotation of the drive shaft 13; The contacts 25 also may berounded as at 25b to avoid the concentration of voltage stresses.

The embodiment of the'invention disclosed in Figures.

2 4 and 5 is generally similar to the embodiment previously described,with the exception of the construction 'of' the piates on which themovable contact elements 25 are mounted. in the modified embodiment ofthe invention each of the mounting plates 15a is provided with a substantially elliptical opening 1611 having; its major axis lying alongthelongitudinal axis of the plate 15a so as to provide a gap Zita betweenthe plate 15a and the driving and. which comprises a shouldered pin3(lahaving a re duce'd end portion 35 received in an opening 36 in. one

rent passing therethrough to add to the mechanical force.

of'the plates 15a and an enlarged portion 35a received inta'n opening3''] in the other plate 15a. the pin Silo between the plates 15a isa'spring 38 which bears against each of the plates 15a and urges them insuch directions as. to cause the contacts 25tto move to Wards oneanother and grip the stationary contact ele ments 2 sandwichedtherebetween. Retention of the pin Mia may be assured by peening over hefree end of the reduced end portion 35 as is'indicatedat 351).

In the construction shown in Figures 4 and 5 the struc ture andarrangement of the mounting plates 15a and the yieldable means 2% aresuch that the driving shaft 13 is interposed'between the yieldable meansand the bridging contacts 25, whereas in the embodiment of the inventionshown in Figures 1 and 2 the construction and arrangement of themounting plates 15 and the yieldable means 29 are such that theyieldable' means is interposed between the drive shaft 13 and themovable contacts 25. v In all other respectahowever, the two embodimentsare similar and the operation of the two embodiments is identical.

Apparatus constructed in accordance with either emoodirnent of theinvention not only has the desirable characteristics referred to above,but also possesses the advantages of known constructions. For examplethe contact members 25 are maintained in substantial parallelism so asto enable the magnetic forces created by curby which the stationarycontacts are gripped. Furthermore, backlash is not required to obtainthe self-aligning action of the contacts 25. Moreover, all electricalenergy carrying parts are isolated by insulating materialandaresupported in spaced relation to the mounting panel so as to.minimizethe formation of sludge. An addi- Surrounding tional advantageof the disclosed embodiments is the as to be mounted in an insulatedtube, thereby allowing the unit to be nested between the coils of atransformer.

The disclosed embodiments are respresentative of presently preferredforms of the invention, but are intended to be illustrative rather thandefinitive thereof. The invention is defined in the claims.

I claim:

1. A rotary switch construction comprising a mounting panel; a pluralityof electrically conductive contact elements; means mounting said contactelements on said panel in spaced apart, arcuate form and spaced fromsaid panel; a rotary driving element located at the center of the arcdefined by said contact elements; apair of spaced apart, superposed,generally parallel support members formed of insulating material andextending radially from said driving element towards the arc defined bysaid contact elements; pivotal means drivingly mounting each of saidsupport members on said driving element for rotation with the latterabout the axis of rotation of said driving element and for-movement ofthe radially outer ends of said support members towards and away fromone another about spaced axes defined by their respective pivotal means;an elongate, electrically conductive contact member for each of saidsupport members and being of such length as to bridge the space betweenand engage opposite sides of any adjacent two of said contact elements;pivotal means mounting each of said contact members on its respectivesupport member adjacent to the radially outer end thereof for rotationabout an axis substantially parallel to and fixed with respect to itsrespective support member; limit means on each of said support memberscooperable with said contact members for limiting rotation of thelatter; and yieldable means reacting on said support members remote fromsaid contact members for yieldably urging the radially outer endsthereof and said contact members towards one another.

'2. The construction set forth in claim 1 wherein said yieldable meansreacts intermediate said driving element and the radially outer ends ofsaid support members.

3. The construction set forth in claim 1 wherein said supporting membersinclude extensions projecting from the axis of rotation of said drivingelement in a direction opposite from said radially outer ends, andwherein said yieldable means reacts on said extensions.

References Cited in the file of this patent UNITED STATES PATENTS

